WLC 4402 DHCP issue

Unanswered Question
Aug 13th, 2007
User Badges:

I am having a problem with getting dhcp to work with our WLC 4402 with 1131ag aps. The ap's will associate with the controller and the client's associate with the ap but they do not get an ip address. The dhcp server is on a different subnet than the WLAN I have created on the controller. The controller can ping the dhcp server and the gateway of every subnet except the gateway of the wireless vlan. I turned on dhcp debugging on the controller and this is what was logged.

Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 Invalid MSCB state: ipAddr=0.0.0.0, regType=2, Dhcp required!


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 dhcpProxy: Received packet: Client 00:0d:93:ed:e6:97


DHCP Op: BOOTREQUEST(1), IP len: 300, switchport: 29, encap: 0xec03


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 dhcpProxy: dhcp request, client: 00:0d:93:ed:e6:97:


dhcp op: 1, port: 29, encap 0xec03, old mscb port number: 29


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 Determing relay for 00:0d:93:ed:e6:97


dhcpServer: 0.0.0.0, dhcpNetmask: 0.0.0.0,


dhcpGateway: 0.0.0.0, dhcpRelay: 172.17.20.31 VLAN: 50


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 Relay settings for 00:0d:93:ed:e6:97


Local Address: 172.17.20.31, DHCP Server: 172.16.10.20,


Gateway Addr: 172.17.20.1, VLAN: 50, port: 29


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 DHCP Message Type received: DHCP DISCOVER msg


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 op: BOOTREQUEST, htype: Ethernet, hlen: 6, hops: 1


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 xid: 1479053852, secs: 43, flags: 0


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 chaddr: 00:0d:93:ed:e6:97


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 ciaddr: 0.0.0.0, yiaddr: 0.0.0.0


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 siaddr: 0.0.0.0, giaddr: 172.17.20.31


Mon Aug 13 18:08:34 2007: DHCP: ARPing for 172.17.20.1, srcIP: 172.17.20.31 vlanId=50


Mon Aug 13 18:08:34 2007: 00:0d:93:ed:e6:97 Determing relay for 00:0d:93:ed:e6:97


dhcpServer: 0.0.0.0, dhcpNetmask: 0.0.0.0,


dhcpGateway: 0.0.0.0, dhcpRelay: 172.17.20.31 VLAN: 50


Mon Aug 13 18:08:35 2007: 00:0d:93:ed:e6:97 Invalid MSCB state: ipAddr=0.0.0.0, regType=2, Dhcp required!


Mon Aug 13 18:08:35 2007: 00:0d:93:ed:e6:97 Invalid MSCB state: ipAddr=0.0.0.0, regType=2, Dhcp required!


Any suggestions on what could be wrong with my configuration?


Thanks in advance.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
frankzehrer Mon, 08/13/2007 - 20:46
User Badges:
  • Silver, 250 points or more

Hi Jeff,


did you configured the DHCP option 43?

This is a wide area of problems, but the main task is to understand the LWAPP and its mechanisms to configure everything properly.

Have a look for the deployment guide:

http://www.cisco.com/en/US/docs/wireless/technology/controller/deployment/guide/dep.html#wp1068287


Especially the Appendix C: How the Vendor-Specific DHCP Option (Option 43) is Used to Faclitate Controller Discovery

http://www.cisco.com/en/US/docs/wireless/technology/controller/deployment/guide/dep.html#wp1068287


The most wireless people struggled with this the first time touching the LWAPP.

;-)


Good luck,


Frank

sbarasiscom Tue, 08/14/2007 - 00:12
User Badges:

As I understood:

You are talking about DHCP 43 which is give IP address to the APs,

But his problem is give IP address to the client..



frankzehrer Tue, 08/14/2007 - 00:22
User Badges:
  • Silver, 250 points or more

Hi Salem,


thanks for the correction. Firewall is a good point.

A firewall may also be an ACL configured on a router or switch.


Another may be the different subnet. Maybe the useage of an "ip helper address" is needed to forward the dhcp between the subnets.


Best regards,

Frank

cef2lion2 Tue, 08/14/2007 - 06:28
User Badges:

I'm having a similar issue on another recent post about a WLC 4402 and DHCP. We are not in control of the head of our network so I can only ask about testing the ip helper suggestion. I think that is our issue.


Craig

erki1 Tue, 08/14/2007 - 10:03
User Badges:

I have had the same problem. The WLC has to be on the same subnet as the DHCP server for the DHCP requests from the AP's to be re-directed by the management interface to the DHCP server. I presume you have a IP-Helper address on your remote routers interface?


Do you have a copy of your config?

frankzehrer Tue, 08/14/2007 - 22:49
User Badges:
  • Silver, 250 points or more

Hi Colin,


i have running the WLC in a different subnet than the DHCP Server. The ip helper solved my problem.


Best regards,

Frank

remco.gussen Wed, 08/15/2007 - 22:27
User Badges:

Every VLAN that is configured on the WLC, can be assigned an ip address. This is an address that is responsible for the "dhcp relay". This address must be in the same subnet as the clients. The WLC forwards DHCP requests from the clients (via this VLAN address on WLC) to the DHCP server. The DHCP server can see the ip address of the WLC (from the correct VLAN) an returns an address from the correct pool.

I had the same problem an this solved it !


Gr.

Remco

sbarasiscom Fri, 08/17/2007 - 22:50
User Badges:

Can we disable dhcp relay in WLC, as my WLC behind the firewall and my DHCP server internally, So the clients in this case couldn't get IP address?????


Please update me ASAP


remco.gussen Sat, 08/18/2007 - 03:21
User Badges:

I also tried that. The WLC intercepts all the DHCP request packets. It is functionating as a DHCP relay agent. When you disable the relay function, the DHCP server doesn't know for which subnet the request is. It wil not work..


Gr.

Remco

sbarasiscom Sat, 08/18/2007 - 04:03
User Badges:

O.K , but do you know how I can solve my problem as

1) the firewall could works as relay for DHCP server (which is inside in my case)


2) the firewall didn't allow anothe relay for DHCP server (which is happen in WLC)as the WLC in (DMZ),


So is there solution for the same design or I have to change the design.


Thanks Friends

Actions

This Discussion

 

 

Trending Topics: Other Wireless Mobility

client could not be authenticated
Network Analysis Module (NAM) Products
Cisco 6500 nam
reason 440 driver failure
Cisco password cracker
Cisco Wireless mode